Possible Causes & Corrections

Check the following items:

• Search for bulletins.
• Test fuel system circuits for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis in FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
• Test for low fuel pressure. Refer to FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
• Test for faulty fuel injectors. Refer to FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L AZTEK & RENDEZVOUS article.
• Inspect for fuel contamination.
• Inspect any items which may cause an engine to run rich. Using scan tool, long term fuel trim is significantly in the negative range.
• Inspect any items which may cause an engine to run lean. Using scan tool, long term fuel trim is significantly in the positive range.
• Inspect for conditions which may cause an incorrect idle speed: Throttle body tampering, excessive deposits or damage. Check for restricted air intake system or large vacuum leak. Check for collapsed air intake ducts. Check for improper installation or leaks especially between the MAF sensor and throttle body.
• Inspect Throttle Position (TP) sensor and related circuit wiring. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article.
• Monitor the 24X crank sensor and CMP sensor signal parameters on scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Test all CKP sensor "A" and CMP sensor circuits for intermittents.
• Monitor the 3X crank sensor parameter on the scan tool. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. If 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a DTC immediately, but are capable of causing driveability complaints.
• Test CKP sensor "B" for an internal short. Refer to Electronic Ignition System diagnosis under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L AZTEK & RENDEZVOUS article.
• Test EGR system for proper operation. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article.
• Test PCV valve for proper operation. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L AZTEK & RENDEZVOUS article.
• Inspect the transaxle range switch input with vehicle in Drive and the gear selector in Drive or Overdrive.
• Inspect for bent balancer interrupter rings or damaged crankshaft position sensor.
• Inspect for proper ignition voltage output using Spark Tester (J-26792).
• If spark is not present at the coils, inspect for coils for cracks, carbon tracking/arcing, or a resistance value that is out of range (5000-800 ohms). Check spark plug wires for signs of arcing, crossfiring, cracks, carbon tracking, plug boot damage, pinched, or improper routing. Check spark plug wire resistance (3000 ohms per foot). Check for defective ignition module, ignition system wiring, loose ignition module feed or ground connection, or damaged system wiring.
• Remove spark plugs and inspect for fouled plugs, cracks, wear, improper gap, burned or damaged electrodes, improper heat range or reach. Check if spark plugs are gas or oil fouled. Cause of fouling must be determined before replacing the spark plugs. Check compression. Refer to MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article. Low compression can be caused by sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms or broken valve springs. Check for excessive oil in combustion chamber. Check for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc.
• Inspect exhaust system for possible restrictions. Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. Check for possible plugged catalytic converter.
• An engine miss condition can be caused by Electromagnetic Interference (EMI) on the reference circuit. EMI can usually be detected by monitoring engine RPM with a scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present. If a problem exists, inspect routing of secondary ignition wires or high voltage components near ignition control circuits.